1. Field of the Invention
The present invention relates to engine diagnostics and, in particular, to an improved apparatus and method for verifying the operation of the fuel injectors.
2. Description of the Related Art
Outboard motors are used to power boats and other watercraft. Outboard motors typically include an internal combustion engine that is surrounded by a protective cowling. The internal combustion engine drives a propulsion device such as, for example, a propeller.
In order to improve performance and in particular fuel efficiency and emissions, many outboard motors use a fuel injection system for supplying fuel to the engine. Fuel injection systems typically include fuel injectors that inject fuel into either an air induction device or into a combustion chamber. The fuel injectors typically are opened and closed by electronic actuators, such as, for example, solenoid valves. The electronic actuators, in turn, are controlled by a control system, which usually includes an electronic control unit (ECU). The ECU determines when to open and close the fuel injectors based upon various ambient conditions and engine operating conditions. The fuel injection system therefore improves engine performance by precisely controlling the fuel/air ratio over a wide range of conditions.
As with other types of engines, outboard motors typically include a diagnostic system. The diagnostic system is configured to indicate engine malfunctions and test various engine components. For example, in engines with fuel injection systems, it is desirable to verify that the fuel injectors and their actuators are operating properly. Accordingly, diagnostic systems are configured such that the fuel injectors can be opened and closed while the engine is not operating. By listening to the opening and the closing of the fuel injectors, a technician can verify that the fuel injectors are functioning. There are, however, several problems associated with these types of tests. For example, during the fuel injector test, a large electrical current is applied to the actuators. This causes the fuel injectors to become hot, which can lead to damage.
Thus, it is an object of the present invention to provide an engine diagnosis system in which the operation of the fuel injectors can be verified without heating the fuel injectors.
Accordingly, one aspect of the of the present invention involves a method for verifying the operation of a fuel injector in a fuel injected engine. The engine includes an electronic control unit that is operatively connected to an actuator configured to open and close the fuel injector. The engine also includes a fuel pump that supplies fuel to the fuel injector. The fuel pump is operated while the engine is generally not in operation. The fuel injector is operated. The diagnostic system determines if the fuel injector has been operating for a specified amount of time. The operation of the fuel injector is stopped if the fuel injector has been operating for a predetermined amount of time. The operation of the fuel pump is then stopped.
Another aspect of the of the present invention involves a diagnostic system for aiding a technician or engineer in verifying that a fuel injector in a fuel injected engine is operating properly. The diagnostic system comprises a controller operatively coupled to an actuator for the fuel injector and to a fuel pressure sensor. The controller is configured such that, during a fuel injector test, the controller outputs a signal to the fuel pump so that pressurized fuel is supplied to the fuel injector. After the pressurized fuel is supplied to the fuel injector, the controller outputs a signal to the actuator to operate the fuel injector for a predetermined amount of time. The controller is also configured such that after the predetermined amount of time the fuel pump is turned off.
Yet another aspect of the present invention involves a method for verifying the operation of a fuel injector in a fuel injected engine. The engine includes an electronic control unit that is operatively connected to an actuator configured to open and close the fuel injector and a fuel pump that supplies fuel to the fuel injector. The fuel injector is operated while the engine is generally not in operation. Fuel is passed through the fuel injector at a reduced fuel pressure in comparison to the fuel pressure present in the fuel injector when the engine is in operation. The operation of the fuel injector is stopped after the fuel injector has been operating for a predetermined amount of time.